In clinical practice, there are various tissues or compartments in which a catheter can be inserted by means of a needle for medical use. Among these, for example, the epidural space, one of those most sought for locoregional anesthesia and for the treatment of pain, deserves special attention. Locating the epidural space is currently a subjective method, known as loss of resistance. Such a method is based on the operator's perception of the loss of resistance offered by the piston of a low pressure syringe when the needle-syringe system advances towards the epidural space. In fact, the epidural space is identified by the perception to the touch of the loss of resistance due to the needle passing the yellow ligament, Because of the several false positives, this technique is not particularly accurate and can cause various complications, including accidental dural puncture. Dural puncture causes the leakage of fluid from the dura mater which in turn causes a prolonged and debilitating headache, resulting in longer hospital stay associated with an increase in hospital costs.
In addition to the problem of the needle reaching the epidural space, a large number of epidural anesthesia failures occur because of the wrong positioning or dislocation of the catheter, which take place upon the needle placement. In fact, once the needle has reached the epidural space, or rather once the operator believes to have reached the epidural space, the catheter is manually inserted into the needle and slid therein. The catheter is slid by pushing it with the fingers. In particular, the catheter is slid until it emerges from the needle tip in order to reach the epidural space.
In detail, the wrong positioning may be due to the accidental insertion of the catheter in an intervertebral foramen and sometimes to the exit from the foramen in the paravertebral space. If the catheter ends in the intervertebral foramen, the anesthesia will be incomplete; if it ends in the paravertebral space, the anesthesia will be failed. The intervertebral foramina are lateral to the interlaminar space through which the epidural needle is inserted. Therefore, when the catheter reaches an intervertebral foramen, it undergoes progressive buckling, up to about 90°. In other words, a kinking of the catheter occurs.
The wrong positioning may also be due to the fictitious operator's perception of the location of the epidural space. In this case, by encountering resistance during the advance, the catheter is crushed upon exiting from the needle.
In, addition, the displacement of the catheter may occur due to the catheter traction during the patient's passive or active movement.
The whole operation is particularly complicated also because when the operator believes that the needle has reached the epidural space, he/she must hold the needle locked with one hand and release the syringe with the other hand and take the catheter from the support cart and insert it through the needle into the epidural space. Control with one hand can often result in the loss of the epidural space, and therefore in a failure of the epidural anesthesia.
Document WO2012/159000A2 describes a device which only allows the movement of a catheter inside a needle. To this end, it is provided with free revolving rolls. The device described in this document does not in any way assists the operator in the search for a specific tissue or biological space like the epidural space.
Document US2015/190123A1 describes a catheter comprising a plurality of optical fibers, each provided with a plurality of sensors. This type of catheter is specifically designed for complex applications, in particular for the shape sensing, and therefore requires a complex construction.
Document U.S. Pat. No. 8,050,523B2 also describes a specific catheter, of the steerable type and quite complex.
The need of overcoming the above drawbacks is therefore felt.